""" The config module holds package-wide configurables and provides a uniform API for working with them. Overview ======== This module supports the following requirements: - options are referenced using keys in dot.notation, e.g. "x.y.option - z". - keys are case-insensitive. - functions should accept partial/regex keys, when unambiguous. - options can be registered by modules at import time. - options can be registered at init-time (via core.config_init) - options have a default value, and (optionally) a description and validation function associated with them. - options can be deprecated, in which case referencing them should produce a warning. - deprecated options can optionally be rerouted to a replacement so that accessing a deprecated option reroutes to a differently named option. - options can be reset to their default value. - all option can be reset to their default value at once. - all options in a certain sub - namespace can be reset at once. - the user can set / get / reset or ask for the description of an option. - a developer can register and mark an option as deprecated. - you can register a callback to be invoked when the option value is set or reset. Changing the stored value is considered misuse, but is not verboten. Implementation ============== - Data is stored using nested dictionaries, and should be accessed through the provided API. - "Registered options" and "Deprecated options" have metadata associated with them, which are stored in auxiliary dictionaries keyed on the fully-qualified key, e.g. "x.y.z.option". - the config_init module is imported by the package's __init__.py file. placing any register_option() calls there will ensure those options are available as soon as pandas is loaded. If you use register_option in a module, it will only be available after that module is imported, which you should be aware of. - `config_prefix` is a context_manager (for use with the `with` keyword) which can save developers some typing, see the docstring. """ import re from collections import namedtuple from contextlib import contextmanager import warnings from pandas.compat import map, lmap, u import pandas.compat as compat DeprecatedOption = namedtuple('DeprecatedOption', 'key msg rkey removal_ver') RegisteredOption = namedtuple('RegisteredOption', 'key defval doc validator cb') _deprecated_options = {} # holds deprecated option metdata _registered_options = {} # holds registered option metdata _global_config = {} # holds the current values for registered options _reserved_keys = ['all'] # keys which have a special meaning class OptionError(AttributeError, KeyError): """Exception for pandas.options, backwards compatible with KeyError checks """ # # User API def _get_single_key(pat, silent): keys = _select_options(pat) if len(keys) == 0: if not silent: _warn_if_deprecated(pat) raise OptionError('No such keys(s): {pat!r}'.format(pat=pat)) if len(keys) > 1: raise OptionError('Pattern matched multiple keys') key = keys[0] if not silent: _warn_if_deprecated(key) key = _translate_key(key) return key def _get_option(pat, silent=False): key = _get_single_key(pat, silent) # walk the nested dict root, k = _get_root(key) return root[k] def _set_option(*args, **kwargs): # must at least 1 arg deal with constraints later nargs = len(args) if not nargs or nargs % 2 != 0: raise ValueError("Must provide an even number of non-keyword " "arguments") # default to false silent = kwargs.pop('silent', False) if kwargs: msg = '_set_option() got an unexpected keyword argument "{kwarg}"' raise TypeError(msg.format(list(kwargs.keys())[0])) for k, v in zip(args[::2], args[1::2]): key = _get_single_key(k, silent) o = _get_registered_option(key) if o and o.validator: o.validator(v) # walk the nested dict root, k = _get_root(key) root[k] = v if o.cb: if silent: with warnings.catch_warnings(record=True): o.cb(key) else: o.cb(key) def _describe_option(pat='', _print_desc=True): keys = _select_options(pat) if len(keys) == 0: raise OptionError('No such keys(s)') s = u('') for k in keys: # filter by pat s += _build_option_description(k) if _print_desc: print(s) else: return s def _reset_option(pat, silent=False): keys = _select_options(pat) if len(keys) == 0: raise OptionError('No such keys(s)') if len(keys) > 1 and len(pat) < 4 and pat != 'all': raise ValueError('You must specify at least 4 characters when ' 'resetting multiple keys, use the special keyword ' '"all" to reset all the options to their default ' 'value') for k in keys: _set_option(k, _registered_options[k].defval, silent=silent) def get_default_val(pat): key = _get_single_key(pat, silent=True) return _get_registered_option(key).defval class DictWrapper(object): """ provide attribute-style access to a nested dict""" def __init__(self, d, prefix=""): object.__setattr__(self, "d", d) object.__setattr__(self, "prefix", prefix) def __setattr__(self, key, val): prefix = object.__getattribute__(self, "prefix") if prefix: prefix += "." prefix += key # you can't set new keys # can you can't overwrite subtrees if key in self.d and not isinstance(self.d[key], dict): _set_option(prefix, val) else: raise OptionError("You can only set the value of existing options") def __getattr__(self, key): prefix = object.__getattribute__(self, "prefix") if prefix: prefix += "." prefix += key try: v = object.__getattribute__(self, "d")[key] except KeyError: raise OptionError("No such option") if isinstance(v, dict): return DictWrapper(v, prefix) else: return _get_option(prefix) def __dir__(self): return list(self.d.keys()) # For user convenience, we'd like to have the available options described # in the docstring. For dev convenience we'd like to generate the docstrings # dynamically instead of maintaining them by hand. To this, we use the # class below which wraps functions inside a callable, and converts # __doc__ into a property function. The doctsrings below are templates # using the py2.6+ advanced formatting syntax to plug in a concise list # of options, and option descriptions. class CallableDynamicDoc(object): def __init__(self, func, doc_tmpl): self.__doc_tmpl__ = doc_tmpl self.__func__ = func def __call__(self, *args, **kwds): return self.__func__(*args, **kwds) @property def __doc__(self): opts_desc = _describe_option('all', _print_desc=False) opts_list = pp_options_list(list(_registered_options.keys())) return self.__doc_tmpl__.format(opts_desc=opts_desc, opts_list=opts_list) _get_option_tmpl = """ get_option(pat) Retrieves the value of the specified option. Available options: {opts_list} Parameters ---------- pat : str Regexp which should match a single option. Note: partial matches are supported for convenience, but unless you use the full option name (e.g. x.y.z.option_name), your code may break in future versions if new options with similar names are introduced. Returns ------- result : the value of the option Raises ------ OptionError : if no such option exists Notes ----- The available options with its descriptions: {opts_desc} """ _set_option_tmpl = """ set_option(pat, value) Sets the value of the specified option. Available options: {opts_list} Parameters ---------- pat : str Regexp which should match a single option. Note: partial matches are supported for convenience, but unless you use the full option name (e.g. x.y.z.option_name), your code may break in future versions if new options with similar names are introduced. value : new value of option. Returns ------- None Raises ------ OptionError if no such option exists Notes ----- The available options with its descriptions: {opts_desc} """ _describe_option_tmpl = """ describe_option(pat, _print_desc=False) Prints the description for one or more registered options. Call with not arguments to get a listing for all registered options. Available options: {opts_list} Parameters ---------- pat : str Regexp pattern. All matching keys will have their description displayed. _print_desc : bool, default True If True (default) the description(s) will be printed to stdout. Otherwise, the description(s) will be returned as a unicode string (for testing). Returns ------- None by default, the description(s) as a unicode string if _print_desc is False Notes ----- The available options with its descriptions: {opts_desc} """ _reset_option_tmpl = """ reset_option(pat) Reset one or more options to their default value. Pass "all" as argument to reset all options. Available options: {opts_list} Parameters ---------- pat : str/regex If specified only options matching `prefix*` will be reset. Note: partial matches are supported for convenience, but unless you use the full option name (e.g. x.y.z.option_name), your code may break in future versions if new options with similar names are introduced. Returns ------- None Notes ----- The available options with its descriptions: {opts_desc} """ # bind the functions with their docstrings into a Callable # and use that as the functions exposed in pd.api get_option = CallableDynamicDoc(_get_option, _get_option_tmpl) set_option = CallableDynamicDoc(_set_option, _set_option_tmpl) reset_option = CallableDynamicDoc(_reset_option, _reset_option_tmpl) describe_option = CallableDynamicDoc(_describe_option, _describe_option_tmpl) options = DictWrapper(_global_config) # # Functions for use by pandas developers, in addition to User - api class option_context(object): """ Context manager to temporarily set options in the `with` statement context. You need to invoke as ``option_context(pat, val, [(pat, val), ...])``. Examples -------- >>> with option_context('display.max_rows', 10, 'display.max_columns', 5): ... """ def __init__(self, *args): if not (len(args) % 2 == 0 and len(args) >= 2): raise ValueError('Need to invoke as' 'option_context(pat, val, [(pat, val), ...)).') self.ops = list(zip(args[::2], args[1::2])) def __enter__(self): undo = [] for pat, val in self.ops: undo.append((pat, _get_option(pat, silent=True))) self.undo = undo for pat, val in self.ops: _set_option(pat, val, silent=True) def __exit__(self, *args): if self.undo: for pat, val in self.undo: _set_option(pat, val, silent=True) def register_option(key, defval, doc='', validator=None, cb=None): """Register an option in the package-wide pandas config object Parameters ---------- key - a fully-qualified key, e.g. "x.y.option - z". defval - the default value of the option doc - a string description of the option validator - a function of a single argument, should raise `ValueError` if called with a value which is not a legal value for the option. cb - a function of a single argument "key", which is called immediately after an option value is set/reset. key is the full name of the option. Returns ------- Nothing. Raises ------ ValueError if `validator` is specified and `defval` is not a valid value. """ import tokenize import keyword key = key.lower() if key in _registered_options: msg = "Option '{key}' has already been registered" raise OptionError(msg.format(key=key)) if key in _reserved_keys: msg = "Option '{key}' is a reserved key" raise OptionError(msg.format(key=key)) # the default value should be legal if validator: validator(defval) # walk the nested dict, creating dicts as needed along the path path = key.split('.') for k in path: if not bool(re.match('^' + tokenize.Name + '$', k)): raise ValueError("{k} is not a valid identifier".format(k=k)) if keyword.iskeyword(k): raise ValueError("{k} is a python keyword".format(k=k)) cursor = _global_config msg = "Path prefix to option '{option}' is already an option" for i, p in enumerate(path[:-1]): if not isinstance(cursor, dict): raise OptionError(msg.format(option='.'.join(path[:i]))) if p not in cursor: cursor[p] = {} cursor = cursor[p] if not isinstance(cursor, dict): raise OptionError(msg.format(option='.'.join(path[:-1]))) cursor[path[-1]] = defval # initialize # save the option metadata _registered_options[key] = RegisteredOption(key=key, defval=defval, doc=doc, validator=validator, cb=cb) def deprecate_option(key, msg=None, rkey=None, removal_ver=None): """ Mark option `key` as deprecated, if code attempts to access this option, a warning will be produced, using `msg` if given, or a default message if not. if `rkey` is given, any access to the key will be re-routed to `rkey`. Neither the existence of `key` nor that if `rkey` is checked. If they do not exist, any subsequence access will fail as usual, after the deprecation warning is given. Parameters ---------- key - the name of the option to be deprecated. must be a fully-qualified option name (e.g "x.y.z.rkey"). msg - (Optional) a warning message to output when the key is referenced. if no message is given a default message will be emitted. rkey - (Optional) the name of an option to reroute access to. If specified, any referenced `key` will be re-routed to `rkey` including set/get/reset. rkey must be a fully-qualified option name (e.g "x.y.z.rkey"). used by the default message if no `msg` is specified. removal_ver - (Optional) specifies the version in which this option will be removed. used by the default message if no `msg` is specified. Returns ------- Nothing Raises ------ OptionError - if key has already been deprecated. """ key = key.lower() if key in _deprecated_options: msg = "Option '{key}' has already been defined as deprecated." raise OptionError(msg.format(key=key)) _deprecated_options[key] = DeprecatedOption(key, msg, rkey, removal_ver) # # functions internal to the module def _select_options(pat): """returns a list of keys matching `pat` if pat=="all", returns all registered options """ # short-circuit for exact key if pat in _registered_options: return [pat] # else look through all of them keys = sorted(_registered_options.keys()) if pat == 'all': # reserved key return keys return [k for k in keys if re.search(pat, k, re.I)] def _get_root(key): path = key.split('.') cursor = _global_config for p in path[:-1]: cursor = cursor[p] return cursor, path[-1] def _is_deprecated(key): """ Returns True if the given option has been deprecated """ key = key.lower() return key in _deprecated_options def _get_deprecated_option(key): """ Retrieves the metadata for a deprecated option, if `key` is deprecated. Returns ------- DeprecatedOption (namedtuple) if key is deprecated, None otherwise """ try: d = _deprecated_options[key] except KeyError: return None else: return d def _get_registered_option(key): """ Retrieves the option metadata if `key` is a registered option. Returns ------- RegisteredOption (namedtuple) if key is deprecated, None otherwise """ return _registered_options.get(key) def _translate_key(key): """ if key id deprecated and a replacement key defined, will return the replacement key, otherwise returns `key` as - is """ d = _get_deprecated_option(key) if d: return d.rkey or key else: return key def _warn_if_deprecated(key): """ Checks if `key` is a deprecated option and if so, prints a warning. Returns ------- bool - True if `key` is deprecated, False otherwise. """ d = _get_deprecated_option(key) if d: if d.msg: print(d.msg) warnings.warn(d.msg, FutureWarning) else: msg = "'{key}' is deprecated".format(key=key) if d.removal_ver: msg += (' and will be removed in {version}' .format(version=d.removal_ver)) if d.rkey: msg += ", please use '{rkey}' instead.".format(rkey=d.rkey) else: msg += ', please refrain from using it.' warnings.warn(msg, FutureWarning) return True return False def _build_option_description(k): """ Builds a formatted description of a registered option and prints it """ o = _get_registered_option(k) d = _get_deprecated_option(k) s = u('{k} ').format(k=k) if o.doc: s += '\n'.join(o.doc.strip().split('\n')) else: s += 'No description available.' if o: s += (u('\n [default: {default}] [currently: {current}]') .format(default=o.defval, current=_get_option(k, True))) if d: s += u('\n (Deprecated') s += (u(', use `{rkey}` instead.') .format(rkey=d.rkey if d.rkey else '')) s += u(')') s += '\n\n' return s def pp_options_list(keys, width=80, _print=False): """ Builds a concise listing of available options, grouped by prefix """ from textwrap import wrap from itertools import groupby def pp(name, ks): pfx = ('- ' + name + '.[' if name else '') ls = wrap(', '.join(ks), width, initial_indent=pfx, subsequent_indent=' ', break_long_words=False) if ls and ls[-1] and name: ls[-1] = ls[-1] + ']' return ls ls = [] singles = [x for x in sorted(keys) if x.find('.') < 0] if singles: ls += pp('', singles) keys = [x for x in keys if x.find('.') >= 0] for k, g in groupby(sorted(keys), lambda x: x[:x.rfind('.')]): ks = [x[len(k) + 1:] for x in list(g)] ls += pp(k, ks) s = '\n'.join(ls) if _print: print(s) else: return s # # helpers @contextmanager def config_prefix(prefix): """contextmanager for multiple invocations of API with a common prefix supported API functions: (register / get / set )__option Warning: This is not thread - safe, and won't work properly if you import the API functions into your module using the "from x import y" construct. Example: import pandas.core.config as cf with cf.config_prefix("display.font"): cf.register_option("color", "red") cf.register_option("size", " 5 pt") cf.set_option(size, " 6 pt") cf.get_option(size) ... etc' will register options "display.font.color", "display.font.size", set the value of "display.font.size"... and so on. """ # Note: reset_option relies on set_option, and on key directly # it does not fit in to this monkey-patching scheme global register_option, get_option, set_option, reset_option def wrap(func): def inner(key, *args, **kwds): pkey = '{prefix}.{key}'.format(prefix=prefix, key=key) return func(pkey, *args, **kwds) return inner _register_option = register_option _get_option = get_option _set_option = set_option set_option = wrap(set_option) get_option = wrap(get_option) register_option = wrap(register_option) yield None set_option = _set_option get_option = _get_option register_option = _register_option # These factories and methods are handy for use as the validator # arg in register_option def is_type_factory(_type): """ Parameters ---------- `_type` - a type to be compared against (e.g. type(x) == `_type`) Returns ------- validator - a function of a single argument x , which raises ValueError if type(x) is not equal to `_type` """ def inner(x): if type(x) != _type: msg = "Value must have type '{typ!s}'" raise ValueError(msg.format(typ=_type)) return inner def is_instance_factory(_type): """ Parameters ---------- `_type` - the type to be checked against Returns ------- validator - a function of a single argument x , which raises ValueError if x is not an instance of `_type` """ if isinstance(_type, (tuple, list)): _type = tuple(_type) from pandas.io.formats.printing import pprint_thing type_repr = "|".join(map(pprint_thing, _type)) else: type_repr = "'{typ}'".format(typ=_type) def inner(x): if not isinstance(x, _type): msg = "Value must be an instance of {type_repr}" raise ValueError(msg.format(type_repr=type_repr)) return inner def is_one_of_factory(legal_values): callables = [c for c in legal_values if callable(c)] legal_values = [c for c in legal_values if not callable(c)] def inner(x): from pandas.io.formats.printing import pprint_thing as pp if x not in legal_values: if not any(c(x) for c in callables): pp_values = pp("|".join(lmap(pp, legal_values))) msg = "Value must be one of {pp_values}" if len(callables): msg += " or a callable" raise ValueError(msg.format(pp_values=pp_values)) return inner # common type validators, for convenience # usage: register_option(... , validator = is_int) is_int = is_type_factory(int) is_bool = is_type_factory(bool) is_float = is_type_factory(float) is_str = is_type_factory(str) is_unicode = is_type_factory(compat.text_type) is_text = is_instance_factory((str, bytes)) def is_callable(obj): """ Parameters ---------- `obj` - the object to be checked Returns ------- validator - returns True if object is callable raises ValueError otherwise. """ if not callable(obj): raise ValueError("Value must be a callable") return True